32volts vs 24volt or 12volts

Discussion in 'Boat Design' started by gabriel, Mar 8, 2012.

  1. gabriel
    Joined: Jan 2012
    Posts: 22
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: venezuela

    gabriel Junior Member

    Hi everyone

    I am remodelling a 58ft 1982 Bertram cruiser and most of the electrical parts ( toilets, lightings, bilge pumps, blowers and of course de two detroit diesel engines) run on a 32volts system. The Boat carries two banks of 8 volts batteries each. All the parts that I need to repair or change are very hard to find in 32 volts. All new parts for toilets, lighting etc.. nowadays come in 12V or 24 V.

    Should I switch all my electrical system including my engines alternators and starters to 24 Volt or 12Volts?

    Please let me know pros and cons if any.

  2. gonzo
    Joined: Aug 2002
    Posts: 16,187
    Likes: 1,360, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    A 32 volt system is quite unusual. 12volt parts are easily accessible and way cheaper.
  3. Stumble
    Joined: Oct 2008
    Posts: 1,913
    Likes: 73, Points: 48, Legacy Rep: 739
    Location: New Orleans

    Stumble Senior Member

    I am not familure with 32v systems, but I have seen 12, 24, and 48. The higher the voltage the smaller the wire can be, and the less loss you get from system inefficiency. The downside is that if you use anything other than 12v a lot of appliances will have to use a step down since they aren't made for 24 or 48v, though they are becoming more common.

    The other option is to run two systems, a 12v, a 48, and 110 if you have it, but this of course increases the wiring complexity of the boat substantially.
  4. mydauphin
    Joined: Apr 2007
    Posts: 2,164
    Likes: 53, Points: 48, Legacy Rep: 575
    Location: Florida

    mydauphin Senior Member

    There is a reason you have does on there. 24 volt systems are more efficient for starters and high power motors. 32 volt systems are too much of a pain. I would replace with 24volt for engines, and 12 volt for other system. Windlass are typically 24volt. Working with 24 and 12 is not hard. 32 volt, well complicates things. You can have your alternators and starters in 24volt and have them charge 2 batteries in series, then just pull two circuits for 12 volt off of them. With twin engine and 4 batteries you can work a nice system.
    You can have a separate bank of two batteries for the house batteries. The DD really need those 24v starters to crank over.
  5. Frosty

    Frosty Previous Member

    Surely the availability of 32 volt appliances rules it out immediately.
  6. gabriel
    Joined: Jan 2012
    Posts: 22
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: venezuela

    gabriel Junior Member

    definetely The change of voltage is necessary

    Thanks to everyone. Definetely after reading your postings the change to a lower Voltage is a must. I beleive that a system for 24 Volts for the engines and from there a 12 volts system for the rest of the boat sounds very logical.
    But will this be to complicated and to costly?
    Now will this change force me to also change all the wiring sizes of all the boat?
    Does anyone knows where I can get a 24 Volts Alternator for those Detroit Diesel Engines 12V71TI

    Thanks Again
  7. gdoug
    Joined: Mar 2012
    Posts: 9
    Likes: 4, Points: 0, Legacy Rep: 51
    Location: Stuart FL

    gdoug GD

    You should try to get a DC-DC converter. It will be cheaper and less complicated than messing with the engines. 32-24 may be hard to find, but if you look hard enough you can find them. Some have adjustable input & outputs. Try these guys: http://www.zahninc.com/. They make great stuff. Check out the website, but be sure to call and explain your electrical system to them. They have converters that can convert a range of continuously varying dc voltage into a steady output voltage. I think you should investigate this before ripping the harness out of the boat.
    If you want to have it all get both 12 and 24V. Since it's such a large boat & you have many systems I think you should go 24V. 24V will give you the same power as 12V with less current draw (power in watts= voltage*current). Less current means less heat which means more reliability in the long run. Also, since your boat is big you may have a need for larger motors, for a winless or davit etc. 24V motors are going to be more powerful than 12V. Plus it's better to convert voltage down than up if you ever find a need for 12V.

    Good luck w/ the project. My father has a 1988 37 Bertram w/ Detroit 692's. It's an amazing boat. We rebuilt the engines ourselves. If you need any Detroit or Bertram resources let me know. I can try to help you out.

    Hope this was helpful.
  8. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Dieselpro.com has 24V and air starters for these engines.
    Have an electrical engineer recalculate wire sizes before you decide to change the voltage. Heavy current loads like starters, winches or thrusters may need new cables.
  9. whitepointer23

    whitepointer23 Previous Member

    trucks with gm's used to have a series paralell switch, start on 24 and rest of truck on 12 volt.
    Joined: Oct 2002
    Posts: 4,519
    Likes: 111, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    "The DD really need those 24v starters to crank over."

    True in freezing climates , but in "Location: Venezuela" probably not.

    The decision is weather the pain and cost of complete systems replacement will be less than an occasional trip to an electrical shop.

    Starters are quite reliable , tho a spare 32V unit might be a good idea.

    toilets, lightings, bilge pumps, blowers would be easy enough to live with in 32v , although the light bulbs would have to be ordered by the box .

    The many thousand$ for new alternators and starter , along with the required downsizing of the wiring system (fewer amps per wire on 24V way! fewer with 12V) would be a long term hassle with little upside.

    An E bay purchase of a 32v toilet motor , blowers bilge pumps might save thousands of bucks and a years hassle.
  11. Fanie
    Joined: Oct 2007
    Posts: 4,603
    Likes: 174, Points: 63, Legacy Rep: 2484
    Location: Colonial "Sick Africa"

    Fanie Fanie

    The whole outomotive world is based on a 12V system - what ever you can think of is available in 12V. Personally I would stick to 12V, all equipment, lights etc works from 12V. You even get hair dryers and coffe makers in 12V.

    24V is an industry standard, you get some stuff in it, but limited.

    Never heard of 32V - no future if you ask me.

    48V is used in inverters to generate mains for ie backup power for PC's. The reason is you can use smaller batteries and smalled devices for the switching, in my opinion a poor voltage to use even if the wiring is going to be thinner.

    What you should do if you go for 12V is to plan your setup a bit. The idea of having one big system supplying everything is not good unless you fit thick wires over the distances, heavy and expensive.

    Small seperate systems have the advantage that they are easy and cheap to maintain and a problem is easy identified and does not affect everything else.

    If you have a single charger ie a generator you can 'isolate' each system with a high power schotkey diode in the pos supply line. The advantage of these power diodes is they have very little forward drop, almost no losses, and also generate almost no head due to the low forward drop. Same can be used if you have solar panels.
  12. gabriel
    Joined: Jan 2012
    Posts: 22
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: venezuela

    gabriel Junior Member

    Thanks GD



  13. keysdisease
    Joined: Mar 2006
    Posts: 794
    Likes: 43, Points: 28, Legacy Rep: 324
    Location: South Florida USA

    keysdisease Senior Member

    For those of you too young to remember, 32 volt was a big boat standard voltage until about the 1980's. Many boats from that era were 32v and parts were readily accessible. The emergence of the voltage systems based on the 6volts bwere the demise of 32v.

    The higher voltage on a larger boat is necessary to overcome voltage drop on long wire runs, but a 58ft boat really isn't that big. I would switch the engines to 24v and as a budget issue maybe go 12v on everything else. If you are installing something with high demand like elect thrusters or an elect windlass those should be 24v also.

    1 person likes this.

    Joined: Oct 2002
    Posts: 4,519
    Likes: 111, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    "Never heard of 32V - no future if you ask me"

    The USCG used to think ( 1930's) under 40V DC would not be cause for electrocution , so 4 ,,,8volt batts were wired together.

    Worked great to reduce wire sizes, but dated.

    24V is common on most OTR trucks and air craft , so loads of surplus goodies are useful , but not household items like blenders,

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.